What are the different types of rocks?
There are 3 main types of rocks: igneous, sedimentary and metamorphic. Igneous rocks form when magma cools and hardens, either underground or above the surface. Sedimentary rocks form when layers of sediment are compacted and hardened by pressure and cement below the surface. Metamorphic rocks form when existing rocks are changed by heat and pressure. They are often found in mountain belts. \n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n\n The most common rock types are igneous and sedimentary, but metamorphic rocks are also common.